Mass Flow Distribution Designand Performance Analysis Of Multi-Duct Combine Cycle Inlet

With the development of hypersonic propulsion technology,the advantages of combined cycle propulsion system become more and more obvious.Inlet is an indispensable part of combined cycle propulsion system,its performance has a direct impact on engine performance.This proposal therefore suggests an investigation on flow mass distribution of multi-duct combined cycle inelt and three-dimensional inward turning quadri-duct combined cycle inelt.First of all,the relationship between the entrance area of each duct and mass flow distribution of mult-duct combined cycle inlet has been investigated.A fast calculate method of mass flow distribution for multi-duct combined cycle inelt is established.Application of the method in dual-duct and tri-duct combined cycle inelt have been verified,the results show that the mass flow rate relative error of dual-duct combined cycle inelt are less than 7%,and 10%for tri-duct combined cycle inelt during the hole work range.Combined with the fast calculate method,a three-dimensional inward turning quadri-duct combined cycle inlet with two turboj et ducts,an ej ector duct and a ramj et duct was designed,which can work during Mach 0-6+.After numerical simulation investigation under different modes,it was confirmed that the inlet can match the requirement of different engines during the hole work range.During turbojet mode,the total pressure recovery of turbojet ducts can keep above 0.60 under critical back pressure.And under the condition that the inlet can work normally,the performance of turbojet ducts can be improved with shutting down the ejector duct properly.During ejector mode,the effect of ejector duct closure on performance of ejector duct and ramjet duct has been investigated.The results show that,the performance of ejector duct decrease and ramjet duct increase with closing ejector duct,under the condition that the inlet can start.To reach a better performance,the closing degree of ejector duct should be adjusted appropriately depends on the specific thrust requirement of eJjector engine and scramj et engine.During ramj et mode,"shock on lip"is obtained at cruising Mach number,"which leads to a fully mass flow capturing.Confirmation of the inlet performance under mode transition shows that inlet can complete mode transition successfully.During the mode transition from turboj et mode to ejector mode at Mach 2.5,the total pressure recovery of turbojet ducts decrease from 0.37 to 0.30,and ejector duct total pressure recovery keep at 0.60 basically.At the end of mode transition from turbojet mode to ejector mode,the total pressure recovery of ej ector increases to 0.73.During the mode transition from ej ector mode to ramjet mode at Mach 4.0,the total pressure recovery of ejector duct decreases from 0.33 to 0.10,and increases from 0.22 to 0.48 for ramjet duct.To further verify the performance of quadri-duct combined cycle inlet,the aerodynamic model has been designed to wind tunnel model and steady/unsteady wind tunnel test are planned.However,due to the difficulty and long period of model processing,and the tight arrangement of wind tunnel,the wind tunnel test has not been completed yet,the comparison between numerical simulation and experiment needs to be further improved and supplemented.